Project Summary In 2017, UNAIDS estimated that 23% of diagnosed persons living with HIV (PLWH) were not accessing antiretroviral therapy (ART), and 18% of PLWH taking ART had unsuppressed viral loads. The development of sustained-release or long-acting injectable antiretroviral therapy (LAI ART) is an important technological advance that could increase ART uptake and adherence by providing new options to support viral load suppression. Research is urgently needed to understand factors that will drive end-user acceptability, so that developers can iteratively formulate more desirable products and funders can identify and prioritize the products most likely to have high uptake and sustained use. This proposal has the following aims: (1) To design and pilot test a discrete choice experiment (DCE) to identify product and delivery attributes related to LAI ART acceptability among patients in the United States (US), based on our prior work and key informant interviews; (2) To recruit 200 ART nave-individuals and 500 ART-experienced individuals in Seattle and Atlanta for a DCE to estimate LAI ART product preferences and identify patient characteristics associated with acceptability among these two key potential end-user groups; and (3) To design and pilot test a similar DCE instrument for use in Kenya, then recruit 200 ART nave-individuals and 500 ART-experienced individuals in Nairobi to learn about patient preferences in the region most impacted by the HIV epidemic. Innovations in the proposed research include a focus on novel LAI ART products in development, inclusion of two patient perspectives (i.e., those just starting treatment and those considering a switch), and exploration of how individual characteristics including prior ART adherence and treatment outcomes influence patient preferences. Our multidisciplinary team includes clinical researchers, behavioral scientists, and health economists with expertise in DCE design and modeling from the University of Washington (UW), RTI International, and Emory University in the US, and from Kenyatta National Hospital in Kenya. The proposed work will take place at two AIDS Clinical Trials Group clinical research sites in the US (i.e., the UW AIDS Clinical Trials Unit in Seattle and the Ponce de Leon Center in Atlanta), and at two HIV clinics within Kenyatta National Hospital in Nairobi, which has been a site for collaborative research with the UW?s Kenya Research and Training Program for over 25 years. Supported by preliminary studies conducted as part of an ongoing UM1 project to develop LAI ART (AI120176, Ho/Collier, NIAID Targeted Long-Acting Combination Antiretroviral Therapy), the proposed work will advance LAI ART product development efforts by providing key estimates of acceptability and patient preferences, enabling funders, product developers, and policy makers to optimize products for the greatest likelihood of uptake, adherence, and long-term viral suppression.